Cobra, the only thing I can think of is if the cauliflower was crowded on the pans, causing it to steam instead of roast. It should be tender, but not soggy, and just the edges should be crisp. Hope that helps...

I agree that your oven may run cold and the cauliflower may have been too crowded, but also, did you try to cut back on the oil? Because you need the oil to essentially oven fry the cauliflower; otherwise you could just be steaming it.